Green anthracene dye.



UNITED sm ng PATENT OFFICE.

ROBER" E. SCHMIDT, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBEN- FABRIKEN10F ELBER-FELD CO., OF NEW YORK, N. Y., A CORPORATION on NEW YORK.

Patented July 24, 1906.

Application filed December 23,1905. Serial No. 293,111.

To all whom it may concern:

Be it known that I, ROBERT E. SCHMIDT, doctor of philosophy, chemist,(assignor to the FARBENFABRIKEN OF ELBERFnLn-Co, of New York,) residingat 22 Varresbeckerstrasse, Elberfeld, Germany, have invented a new anduseful Improvement in Green Anthracene Dye and I hereby declare thefollowing to be a clear and exact description of my invention.

Alkaline sulfids produce, as is known,when i acting ondinitroanthrarufin disulfonic acid in alkaline solution thediamidoanthrarufin disulfonic acida blue coloring-matter. I

have now found that the reaction proceeds in a different way if it iscarried out in neutral or acid solution. A new coloring-matter is thusobtained which dyes unmordanted wool pure green shades.

The new dyestufi' is after being dried and pulverized in the shape ofits sodium salt a dark-green powder which is soluble in hot acidulatedwater with a green color, very difficultly soluble in dilute causticsoda, and soluble in concentrated sulfuric acid. with a yellowish-redcolor, which turns bluish-red by the addition of boric acid.

In order to produce the new dyestuff, I can proceed as follows, theparts being by weight:

Ten (10) parts of the acid sodium salt of dinitroanthrarufin disulfonicacid are dissolved in seven hundred (700) parts of hot water with theaddition of ten (10) parts of a solution of acetic acid containing fiftyper cent A solution of twenty-five (25) parts of crystallized sodiumsulfid in a hundred (100) parts of Water is then gradually poured intothe mixture through a tube reaching to the bottom of the flask, care being taken that the liquid is stirred at seventylive degrees (75)centigrade. During the first step of the operation, while the liquid isacid, an intermediate compound forms, the

liquid assuming a violet-red color. When the free acid is saturated, thesaid intermedi ate compound is converted into the green dyes'tufi' bythe action of sodium sulfid in excess. By heating to ninety toninety-five (9095) degrees centigrade the color turns greenish blue, thedyestuif separating n small green needles, which are filtered off andwashed with a small quantity of cold water.

the diamidoanthrarufin disulfonic acid.

Having now described my invention and in what manner the same is to beperformed, what I claim as new, and desire to secure by Letters Patent,is-

The herein-described new green dyestuff, obtainable by treatingdinitroanthrarufin disulfonic acid with alkaline sulfids in neutralsolution, which dyestuif is, when dry and pulverized,in the shape of itssodium salt a darkgreen powder soluble in hot acidulated water with agreen color, soluble with great difficulty in dilute caustic soda andbeing soluble in concentrated sulfuric acid with a yellow ish-red colorwhich turns bluish red by the addition of boric acid, substantially asdescribed.

In testimony whereof I have signed my name in the presence of twosubscribing witnesses.

4 ROBERT E. SCHMIDT.

\Vitnesses OTTO KoNie, II. SonMin'r.

